Modified nanoporous carbon as a novel sorbent before solvent-based de-emulsification dispersive liquid-liquid microextraction for ultra-trace detection of cadmium by flame atomic absorption spectrophotometry

Combination of different extraction methods is an interesting work in the field of sample pretreatment. In the current study, for the first time, solid phase extraction combined with solvent-based de-emulsification dispersive liquid-liquid microextraction (SPE-SD-DLLME) was developed for preconcentration and trace detection of cadmium in water samples using flame atomic absorption spectrophotometry (FAAS). The adsorbed cadmium ions on prepared SPE (75 mL of aqueous solution) were eluted by optimized elution solvent and introduced to the second microextraction step. The effective variables of SPE including the pH of sample, flow rates, type, concentration and volume of the eluent and the effect of potentially interfering ions of the separation of cadmium were evaluated and optimized. Also, several factors that influence the SD-DLLME step such as pH, neocuproine concentration (the cadmium binding ligand), type of dispersed/de-emulsifier solvent, volume of disperser/de-emulsifier solvent and type and volume of extraction solvents were investigated. SPE-SD-DLLME provides a preconcentration factor of 165 for cadmium ions. Calibration plot was linear in the range of 0.1-50 mu g L-1 with correlation of determination (r(2)) of 0.988. The precision and limit of detection of proposed method were 5.1% (RSD%, n = 8) and 0.03 mu g L-1, respectively. (C) 2014 Elsevier Ltd. All rights reserved.